Tertiary connection strategy for vehicle originated cellular communication to a call center

ABSTRACT

A system and method for making vehicle originated calls to a telematics service provider or other call center. The method includes identifying a call type associated with a desired wireless communication of speech or data to the call center, and then carrying out one of a number of different call connection processes depending on the call type. For voice channel cellular connections, an in-band modem cellular connection is preferably established in most instances using a connection retry strategy that includes primary, secondary, and possibly tertiary connection attempts. The system and method can be carried out in connection with various cellular system technologies, but is especially suited for use with GSM systems.

TECHNICAL FIELD

The present invention relates generally to techniques for establishingmobile vehicle originated cellular communications from a vehicletelematics unit to a remote call center.

BACKGROUND OF THE INVENTION

Vehicle telematics services carried over a public land mobile network(PLMN) or other wireless carrier system present certain challengesunique to the mobile vehicle application. For example, some vehicletelematics units (VTU) are designed to permit both voice and datacommunications over the wireless carrier system using one or more of thevarious available different transmission technologies, such as 2G CDMA(IS-95), 3G CDMA2000 (IS-2000, 1 XRTT, EVDO), 3G UTMS (W-CDMA, HSPA),2G/2.5G GSM (GPRS and EDGE). Depending on such things as the technologyused, e.g., GSM versus CDMA, the registration or acquisition processrequired, the frequent movement of the vehicle into and out of a homePLMN (HPLMN), the availability of one data transmission protocol versusanother, and the particular type of call being made to or from thevehicle, the VTU may only have one wireless communication protocolavailable and suitable for use, or may have more than one from which itcan select. And while multiple types of wireless transmission may beavailable at any one time, their associated cost of use can vary makingit desirable to judiciously select among them. Similarly, callconnection costs associated with data roaming can be significant and itcan therefore be desirable to implement connection strategies thatminimize roaming and its associated costs.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a connectionmethod for use by a vehicle telematics unit to establish a wirelesstelephone connection between the telematics unit and a call center overa GSM cellular system, comprising the steps of: (a) selecting anavailable PLMN using a manual network selection mode supported by theGSM cellular system; (b) selecting a base station within the selectedPLMN; (c) attempting to attach to the selected base station; (d)attempting origination of a voice channel cellular connection if thetelematics unit is attached to a base station; and (e) iterativelyrepeating steps (a) through (d) for each available PLMN.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more preferred exemplary embodiments of the invention willhereinafter be described in conjunction with the appended drawings,wherein like designations denote like elements, and wherein:

FIG. 1 is a block diagram depicting an exemplary embodiment of acommunications system that is capable of utilizing the method disclosedherein;

FIG. 2 is a flowchart depicting an overview of one embodiment of acommunications method that can be used by a vehicle telematics unit suchas in FIG. 1 to establish a voice or data connection with a call centerin response to an input requesting the connection;

FIG. 3 is a call connection table identifying different call types andcontaining call parameters used by the method of FIG. 2 to determinewhat type of call to establish with the call center;

FIG. 4 is a flowchart showing one embodiment of a voice channel retrymethod for use by a vehicle telematics unit in establishing a voicechannel cellular connection with a call center;

FIG. 5 is a flowchart of a primary connection attempt method used in thevoice channel retry method of FIG. 4;

FIG. 6 is a flowchart of a secondary connection attempt method used inthe retry method of FIG. 4; and

FIG. 7 is a flowchart of a tertiary connection attempt method used inthe retry method of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The system and methods described below can be used by a vehicletelematics unit to establish a vehicle originated voice and/or dataconnection with a call center in response to some initiating inputreceived by the telematics unit. Although the methods described beloware such as they might be implemented for a 2G GSM (GPRS and EDGE)system, it will be appreciated that they could be useful in 3G UTMS(W-CDMA, HSPA) and other types of cellular systems.

Communications System

With reference to FIG. 1, there is shown an exemplary operatingenvironment that comprises a mobile vehicle communications system 10 andthat can be used to implement the methods disclosed herein.Communications system 10 generally includes a vehicle 12, one or morewireless carrier systems 14, a land communications network 16, acomputer 18, and a call center 20. It should be understood that thedisclosed method can be used with any number of different systems and isnot specifically limited to the operating environment shown here. Also,the architecture, construction, setup, and operation of the system 10and its individual components are generally known in the art. Thus, thefollowing paragraphs simply provide a brief overview of one suchexemplary system 10; however, other systems not shown here could employthe disclosed method as well.

Vehicle 12 is depicted in the illustrated embodiment as a passenger car,but it should be appreciated that any other vehicle includingmotorcycles, trucks, sports utility vehicles (SUVs), recreationalvehicles (RVs), marine vessels, aircraft, etc., can also be used. Someof the vehicle electronics 28 is shown generally in FIG. 1 and includesa telematics unit 30, a microphone 32, one or more pushbuttons or othercontrol inputs 34, an audio system 36, a visual display 38, and a GPSmodule 40 as well as a number of vehicle system modules (VSMs) 42. Someof these devices can be connected directly to the telematics unit suchas, for example, the microphone 32 and pushbutton(s) 34, whereas othersare indirectly connected using one or more network connections, such asa communications bus 44 or an entertainment bus 46. Examples of suitablenetwork connections include a controller area network (CAN), a mediaoriented system transfer (MOST), a local interconnection network (LIN),a local area network (LAN), and other appropriate connections such asEthernet or others that conform with known ISO, SAE and IEEE standardsand specifications, to name but a few.

The vehicle telematics unit (VTU) 30 is an OEM-installed device thatenables wireless voice and/or data communication over wireless carriersystem 14 and via wireless networking so that the vehicle cancommunicate with call center 20, other telematics-enabled vehicles, orsome other entity or device. The telematics unit preferably uses radiotransmissions to establish a communications channel (a voice channeland/or a data channel) with wireless carrier system 14 so that voiceand/or data transmissions can be sent and received over the channel. Byproviding both voice and data communication, telematics unit 30 enablesthe vehicle to offer a number of different services including thoserelated to navigation, telephony, emergency assistance, diagnostics,infotainment, etc. Data can be sent either via a data connection, suchas via short message service (SMS) or packet data transmission over adata channel, or via a voice channel using techniques known in the art.For combined services that involve both voice communication (e.g., witha live advisor or voice response unit at the call center 20) and datacommunication (e.g., to provide GPS location data or vehicle diagnosticdata to the call center 20), the system can utilize a single call over avoice channel and switch as needed between voice and data transmissionover the voice channel, and this can be done using techniques known tothose skilled in the art.

According to one embodiment, telematics unit 30 utilizes cellularcommunication according to GSM, W-CDMA, or CDMA standards and thusincludes a standard cellular chipset 50 for voice communications likehands-free calling, a wireless modem for data transmission, anelectronic processing device 52, one or more digital memory devices 54,and a dual antenna 56. It should be appreciated that the modem caneither be implemented through software that is stored in the telematicsunit and is executed by processor 52, or it can be a separate hardwarecomponent located internal or external to telematics unit 30. The modemcan operate using any number of different standards or protocols used inthe wireless industry such as 3gpp or 3gpp2. Wireless networking betweenthe vehicle and other networked devices can also be carried out usingtelematics unit 30. For this purpose, telematics unit 30 can beconfigured to communicate wirelessly according to one or more protocolsimplemented per 3gpp or 3gpp2 standards and also other wirelessprotocols, such as any of the IEEE 802.11 protocols, WiMAX, orBluetooth. When used for packet-switched data communication such asTCP/IP, the telematics unit can be configured with a static IP addressor can be set up to automatically receive a dynamically assigned IPaddress from another device on the network, such as from a router orfrom a network address server (e.g., a DHCP server).

Processor 52 can be any type of device capable of processing electronicinstructions including microprocessors, microcontrollers, hostprocessors, controllers, vehicle communication processors, andapplication specific integrated circuits (ASICs). It can be a dedicatedprocessor used only for telematics unit 30 or can be shared with othervehicle systems. Processor 52 executes various types of digitally-storedinstructions, such as software or firmware programs stored in memory 54,which enable the telematics unit to provide a wide variety of services.For instance, processor 52 can execute programs or process data to carryout at least a part of the method discussed herein.

Telematics unit 30 can be used to provide a diverse range of vehicleservices that involve wireless communication to and/or from the vehicle.Such services include: turn-by-turn directions and othernavigation-related services that are provided in conjunction with theGPS-based vehicle navigation module 40; airbag deployment notificationand other emergency or roadside assistance-related services that areprovided in connection with one or more collision sensor interfacemodules such as a body control module (not shown); diagnostic reportingusing one or more diagnostic modules; and infotainment-related serviceswhere music, webpages, movies, television programs, videogames and/orother information is downloaded by an infotainment module (not shown)and is stored for current or later playback. The above-listed servicesare by no means an exhaustive list of all of the capabilities oftelematics unit 30, but are simply an enumeration of some of theservices that the telematics unit is capable of offering. Furthermore,it should be understood that at least some of the aforementioned modulescould be implemented in the form of software instructions saved internalor external to telematics unit 30, they could be hardware componentslocated internal or external to telematics unit 30, or they could beintegrated and/or shared with each other or with other systems locatedthroughout the vehicle, to cite but a few possibilities. In the eventthat the modules are implemented as VSMs 42 located external totelematics unit 30, they could utilize vehicle bus 44 to exchange dataand commands with the telematics unit.

GPS module 40 receives radio signals from a constellation 60 of GPSsatellites. From these signals, the module 40 can determine vehicleposition that is used for providing navigation and otherposition-related services to the vehicle driver. Navigation informationcan be presented on the display 38 (or other display within the vehicle)or can be presented verbally such as is done when supplying turn-by-turnnavigation. The navigation services can be provided using a dedicatedin-vehicle navigation module (which can be part of GPS module 40), orsome or all navigation services can be done via telematics unit 30,wherein the position information is sent to a remote location forpurposes of providing the vehicle with navigation maps, map annotations(points of interest, restaurants, etc.), route calculations, and thelike. The position information can be supplied to call center 20 orother remote computer system, such as computer 18, for other purposes,such as fleet management. Also, new or updated map data can bedownloaded to the GPS module 40 from the call center 20 via thetelematics unit 30.

Apart from the audio system 36 and GPS module 40, the vehicle 12 caninclude other vehicle system modules (VSMs) 42 in the form of electronichardware components that are located throughout the vehicle andtypically receive input from one or more sensors and use the sensedinput to perform diagnostic, monitoring, control, reporting and/or otherfunctions. Each of the VSMs 42 is preferably connected by communicationsbus 44 to the other VSMs, as well as to the telematics unit 30, and canbe programmed to run vehicle system and subsystem diagnostic tests. Asexamples, one VSM 42 can be an engine control module (ECM) that controlsvarious aspects of engine operation such as fuel ignition and ignitiontiming, another VSM 42 can be a powertrain control module that regulatesoperation of one or more components of the vehicle powertrain, andanother VSM 42 can be a body control module that governs variouselectrical components located throughout the vehicle, like the vehicle'spower door locks and headlights. According to one embodiment, the enginecontrol module is equipped with on-board diagnostic (OBD) features thatprovide myriad real-time data, such as that received from varioussensors including vehicle emissions sensors, and provide a standardizedseries of diagnostic trouble codes (DTCs) that allow a technician torapidly identify and remedy malfunctions within the vehicle. As isappreciated by those skilled in the art, the above-mentioned VSMs areonly examples of some of the modules that may be used in vehicle 12, asnumerous others are also possible.

Vehicle electronics 28 also includes a number of vehicle user interfacesthat provide vehicle occupants with a means of providing and/orreceiving information, including microphone 32, pushbuttons(s) 34, audiosystem 36, and visual display 38. As used herein, the term ‘vehicle userinterface’ broadly includes any suitable form of electronic device,including both hardware and software components, which is located on thevehicle and enables a vehicle user to communicate with or through acomponent of the vehicle. Microphone 32 provides audio input to thetelematics unit to enable the driver or other occupant to provide voicecommands and carry out hands-free calling via the wireless carriersystem 14. For this purpose, it can be connected to an on-boardautomated voice processing unit utilizing human-machine interface (HMI)technology known in the art. The pushbutton(s) 34 allow manual userinput into the telematics unit 30 to initiate wireless telephone callsand provide other data, response, or control input. Separate pushbuttonscan be used for initiating emergency calls versus regular serviceassistance calls to the call center 20. Audio system 36 provides audiooutput to a vehicle occupant and can be a dedicated, stand-alone systemor part of the primary vehicle audio system. According to the particularembodiment shown here, audio system 36 is operatively coupled to bothvehicle bus 44 and entertainment bus 46 and can provide AM, FM andsatellite radio, CD, DVD and other multimedia functionality. Thisfunctionality can be provided in conjunction with or independent of theinfotainment module described above. Visual display 38 is preferably agraphics display, such as a touch screen on the instrument panel or aheads-up display reflected off of the windshield, and can be used toprovide a multitude of input and output functions. Various other vehicleuser interfaces can also be utilized, as the interfaces of FIG. 1 areonly an example of one particular implementation.

Wireless carrier system 14 is preferably a cellular telephone systemthat includes a plurality of cell towers 70 (only one shown), one ormore mobile switching centers (MSCs) 72, as well as any other networkingcomponents required to connect wireless carrier system 14 with landnetwork 16. Each cell tower 70 includes sending and receiving antennasand a base station, with the base stations from different cell towersbeing connected to the MSC 72 either directly or via intermediaryequipment such as a base station controller. Cellular system 14 canimplement any suitable communications technology, including for example,analog technologies such as AMPS, or the newer digital technologies suchas 2G CDMA (IS-95), 3G CDMA2000 (IS-2000, 1XRTT, EVDO), 2G/2.5G GSM(GPRS, EDGE), or 3G W-CDMA (UMTS, HSPA). As will be appreciated by thoseskilled in the art, various cell tower/base station/MSC arrangements arepossible and could be used with wireless system 14. For instance, thebase station and cell tower could be co-located at the same site or theycould be remotely located from one another, each base station could beresponsible for a single cell tower or a single base station couldservice various cell towers, and various base stations could be coupledto a single MSC, to name but a few of the possible arrangements.

Apart from using wireless carrier system 14, a different wirelesscarrier system in the form of satellite communication can be used toprovide uni-directional or bi-directional communication with thevehicle. This can be done using one or more communication satellites 62and an uplink transmitting station 64. Uni-directional communication canbe, for example, satellite radio services, wherein programming content(news, music, etc.) is received by transmitting station 64, packaged forupload, and then sent to the satellite 62, which broadcasts theprogramming to subscribers. Bi-directional communication can be, forexample, satellite telephony services using satellite 62 to relaytelephone communications between the vehicle 12 and station 64. If used,this satellite telephony can be utilized either in addition to or inlieu of wireless carrier system 14.

Land network 16 may be a conventional land-based telecommunicationsnetwork that is connected to one or more landline telephones andconnects wireless carrier system 14 to call center 20. For example, landnetwork 16 may include a public switched telephone network (PSTN) suchas that used to provide hardwired telephony, a packet-switched datanetwork (PSDN), and the Internet infrastructure. One or more segments ofland network 16 could be implemented through the use of a standard wirednetwork, a fiber or other optical network, a cable network, power lines,other wireless networks such as wireless local area networks (WLANs), ornetworks providing broadband wireless access (BWA), or any combinationthereof. Furthermore, call center 20 need not be connected via landnetwork 16, but could include wireless telephony equipment so that itcan communicate directly with a wireless network, such as wirelesscarrier system 14.

Computer 18 can be one of a number of computers accessible via a privateor public network such as the Internet. For example, computer 18 can beconnected to one or more of the other system 10 components via a privateor virtual private network (VPN) implemented through a leased line orInternet ISP in the PSDN. Each such computer 18 can be used for one ormore purposes, such as a web server accessible by the vehicle viatelematics unit 30 and wireless carrier 14. Other such accessiblecomputers 18 can be, for example: a service center computer wherediagnostic information and other vehicle data can be uploaded from thevehicle via the telematics unit 30; a client computer used by thevehicle owner or other subscriber for such purposes as accessing orreceiving vehicle data or to setting up or configuring subscriberpreferences or controlling vehicle functions; or a third partyrepository to or from which vehicle data or other information isprovided, whether by communicating with the vehicle 12 or call center20, or both. A computer 18 can also be used for providing Internetconnectivity such as DNS services or as a network address server thatuses DHCP or other suitable protocol to assign an IP address to thevehicle 12.

Call center 20 is designed to provide the vehicle electronics 28 with anumber of different system back-end functions and, according to theexemplary embodiment shown here, generally includes one or more switches80, servers 82, databases 84, live advisors 86, as well as an automatedvoice response system (VRS) 88, all of which are known in the art. Thesevarious call center components are preferably coupled to one another viaa wired or wireless local area network 90. Switch 80, which can be aprivate branch exchange (PBX) switch, routes incoming signals so thatvoice transmissions are usually sent to either the live adviser 86 byregular phone or to the automated voice response system 88 using VoIP.The live advisor phone can also use VoIP as indicated by the broken linein FIG. 1. VoIP and other data communication through the switch 80 isimplemented via a modem (not shown) connected between the switch 80 andnetwork 90. Data transmissions are passed via the modem to server 82and/or database 84. Database 84 can store account information such assubscriber authentication information, vehicle identifiers, profilerecords, behavioral patterns, and other pertinent subscriberinformation. Data transmissions may also be conducted by wireless localnetwork using protocols such as 802.11x and the like. Although theillustrated embodiment has been described as it would be used inconjunction with a manned call center 20 using live advisor 86, it willbe appreciated that the call center can instead utilize VRS 88 as anautomated advisor or, a combination of VRS 88 and the live advisor 86can be used.

Method

Turning now to FIG. 2, there is shown the overall connection strategy100 for making vehicle originated calls from the telematics unit 30 tothe call center 20. The method of FIG. 2 as well as that of the otherfigures can be carried out using suitable programming of the vehicletelematics unit (VTU) as well as using suitable hardware and programmingof the other components shown in FIG. 1. These features of anyparticular implementation will be known to those skilled in the artbased on the above system description and the discussion of the variousmethods that are described below in conjunction with the remainingfigures. Further, as noted above, although any of a variety of differentwireless communication technologies can be used, the followingdiscussion is directed most specifically to the use of 2G/2.5G GSM (GPRSand EDGE) and also indirectly as part of the network parameters, airinterface and channel scheme for 3G W-CDMA (UMTS and HSPA).

The method of FIG. 2 begins with the step 102 of obtaining a request toconnect to the call center 20. This request is in some form of an inputreceived or otherwise obtained by the telematics unit 30, and the inputis associated with a desired wireless communication of data or othermessage via either a voice communication (speech) or data connectionfrom the vehicle 12 to a call center 20. This initiating input can bereceived from the vehicle LAN (e.g., via bus 44) or from the vehicleuser interface, or from some other source. For example, the input can bea manual input by the vehicle driver or other occupant, such as a buttonpress or voice command to indicate that a call to the call center isdesired. Or, the input can be generated automatically, such as by asensor or controller in response to sensor input. An airbag deploymentsignal, such as is generated by a crash sensor, is one known example ofsensor input that automatically initiates a data connection to the callcenter. Another type of input is a trigger that can be set on thevehicle, such as a software trigger in the telematics unit 30 orelsewhere that, when the trigger occurs, initiates the connection to thecall center. Yet another input is as a response to a received wirelesscommunication from the call center or elsewhere, whether via cellulartelephony, satellite broadcast, or otherwise. In this latter scenario,the telematics unit 30 can initiate the call center call to respond tothe earlier received communication, such as to acknowledge receipt orperformance of some action on the vehicle, or to supply information suchas DTCs or other vehicle data.

Depending on the reason for the call center call, one of a number ofdifferent types of potential connections will be used for communicationof the data or other message back to the call center 20. Thus, the nextstep 104 is to select a call type associated with the desired wirelesscommunication back. This selected call type identifies the type ofconnection being attempted between the VTU and call center; for example,a voice cellular call (i.e., speech conducted over a cellular voicechannel), an in-band modem cellular call (i.e., a modem data connectionestablished over a cellular voice channel), or a non-voice channel (NVC)data connection such as SMS or a packet data connection (e.g., TCP/IPusing GPRS or EDGE). Thus, as one example, for communication of speech,a voice cellular call can be used, whereas for the communication ofdata, either an in-band modem cellular call or a NVC data connection canbe used. Other call types can be used as well. For example, speech canbe communicated using a data connection wherein the speech is digitizedand sent over, for example, a packet data connection.

Selection of the call type can be carried out based on one or more callparameters, such as the content of the desired wireless communication(e.g., an emergency call versus a request for navigation assistanceversus an automatic upload of DTCs or other vehicle data), the source ofthe requesting input for the communication (e.g., manual button press byan occupant versus an automatic input based on a sensor reading versus acall received from the call center), or the intended recipient (e.g.,server 82 versus advisor 86 versus VRS 88). In at least some instances,the selected call type can be a preferred call type with an alternativecall type being specified as a backup. If at some point during theprocess of FIG. 2, the VTU 30 determines that one or more originationattempts using the preferred call type has failed, then the alternativecall type can be used to access and carry out an alternative connectionstrategy. This is shown at block 120. In addition to or in lieu of theuse of an alternative connection strategy, a separate retry track can bespecified to identify a desired level of persistence in attemptingorigination. This is discussed in more detail below.

FIG. 3 depicts a call connection table that contains the various callparameters which relate to different types of communications and whichare useful in selecting a desired call type. Each row of the tablerepresents a different type of message, or communication, to be sent tothe call center 20. Selection of the call type to be used forcommunication of the message can be selected based on a message categoryor, as noted above, can be based on one or more other factors such asthe type or source of initiating input. The message category shown is abroad classification of the content of the communication itself. Ifdesired, one or more other levels of abstraction of the message contentcan be identified and used either for selection of call type or forreporting back to the call center or taking other action. For example,in the illustrated call connection table, there is also provided amessage type, which is a finer classification of the message contentinto a calling code associated with the message contents. This callingcode can be sent to the call center at the establishment of theconnection and used for various purposes, such as to identify whatvehicle data is being uploaded to the call center or how the call oruploaded data should be processed within the call center. The variouscall parameters shown in FIG. 3 are representative of the differentmessages and initiating inputs involved in initiating calls to the callcenter; however, it will be appreciated that many other additional typescould also be used.

As indicated in FIG. 3, for each type of desired wireless communication,there is a preferred call type which, in the illustrated embodiment, iseither a voice cellular call (VCC), an in-band modem cellular call(IMCC), a packet data connection, or an SMS (either binary or text-basedmessaging). Also, in some instances, an alternative call type isidentified, such as in the case of certain preferred packet data calltypes where an IMCC connection attempt can be used as an alternativeconnection strategy if the packet data connection fails. The retry trackidentifies a persistence level that is useful in attempting originationsof voice channel cellular connections so that, for higher prioritycommunications, the VTU will carry out an additional, comprehensiveconnection strategy in the event that other origination attempts fail.

Referring back to FIG. 2, once the call type is selected at step 104,then the process branches based on the selected call type, step 106, andcarries out an appropriate connection strategy associated with theselected call type. For a voice cellular call, which is meant to be usedby an occupant for communicating with the call center advisor or voiceresponse system (VRS) via speech, a voice-only cellular call can beestablished wherein only speech is exchanged with the call center viathe cellular system's voice channel. However, in the embodiment of FIG.2, where the call type is either the voice channel call or the in-bandmodem cellular call, the method moves to block 108 where a voice channelcellular call is established using a voice channel data connection retrystrategy. This approach is done even for voice cellular calls so thatuseful vehicle data can be uploaded to the call center for use by theadvisor or VRS prior to the start of speech. The connection retrystrategy used to establish the voice channel cellular call involves aplurality of different connection methods that are attempted seriallyuntil either one of the methods results in a successful origination, orall fail. In general, the methods each involve attempting to attach to acellular base station, originating a voice channel cellular connectionvia the attached base station, and then establishing a modem dataconnection with the call center over the originated connection. As usedherein, an “attached base station” is, for GSM systems, a base stationfor which the VTU is camped on, is receiving a decodable broadcastcontrol channel (BCCH), and is registered. For CDMA, an “attached basestation” is one on which VTU is registered. Thus, using an attached basestation, the step 108 will carry out a voice channel origination process110 during which the telematics unit attempts origination of the voicechannel cellular connection and, if the connection is made, it will thenestablish the modem data connection to upload the desired data. Thevoice channel data connection retry process and its different connectionmethods are discussed in greater detail below in connection with FIGS.4-7 and the voice channel origination process can be carried out in amanner known to those skilled in the art.

For a NVC data connection call type, the process of FIG. 2 uses aconnection strategy that attempts to establish either a packet dataconnection or an SMS data connection, and the selection between thesetwo types of data connections can be made in any desired manner, such asby using the call connection table of FIG. 3. Where an SMS dataconnection is desired, the process moves from step 106 to 112 where itcarries out an SMS origination process 112 to establish an SMS dataconnection. If successful, then the desired wireless communication canbe transmitted to the call center in the form of a text message. And,where a packet data connection is desired, the process instead movesfrom step 106 to 116 where it carries out a packet data retry processthat attempts a packet data origination 118 to establish the packet dataconnection. If successful, then the desired wireless communication istransmitted as packetized digital data from the vehicle to the callcenter. The SMS origination process 112 and the packet data retryprocess 116 and its origination process 118 can be carried out in amanner known to those skilled in the art.

Where communication with the call center via the preferred call type isnot available, the process can permit an attempted connection via one ofthe other call types as an alternative connection strategy, as indicatedat block 120. The determination as to whether one or more alternativestrategies should be used can be carried out in various ways, such as byusing the call connection table of FIG. 3 to specify for each messagetype or each call type what alternative, if any, is available.

Once a suitable connection is established between the VTU 30 and callcenter 20, the desired wireless communication of speech and/or data issent via that connection. The process of FIG. 2 then ends.

FIG. 4 depicts the voice channel data connection retry process 108 ingreater detail. In the illustrated embodiment, this process is used fororiginating both voice-only calls (speech only) as well as in-band modemcellular calls (IMCCs), although it will be appreciated that, ifdesired, the process could be used to establish other types of vehicleoriginated calls, such as packet data connections and SMS transmissions.The first step is to determine at block 130 which of these two calltypes is being attempted. In most instances, it is desirable even forcalls meant primarily to conduct speech between a vehicle occupant andcall center that an IMCC be established during the first few seconds ofthe call to upload vehicle data, as noted above. For these calls, theprocess moves to step 132 to carry out a primary connection attempt inwhich origination of the IMCC is attempted using either acurrently-attached base station or one that can be attached to via anidle mode process that involves cell reselection and attempting toattach to a base station following cell reselection. The primaryconnection method 132 is further described farther below in connectionwith FIG. 5.

The idle mode process can be implemented using standard GSM procedures.In one implementation, the idle mode process can be carried out usingthe C2 reselection algorithm, as is known to those skilled in the art.Apart from only cell reselection, the GSM idle mode process can performa more complete search for an available base station. For example, theidle mode process used can perform the following procedures: (1) PLMNsection and reselection; (2) Cell selection (C1) and reselection (C2);and (3) location registration. These procedures are known to thoseskilled in the art. For example, PLMN selection can be carried out perTS23.122, cell selection/reselection can be carried out perTS43.022/TS45.008, and location registration for IMSI Attach/Detach canbe carried out per TS23.122/TS23.012. As will be known by those skilledin the art, in implementing the idle mode process, the search for a PLMNcan be limited to the access technology or access technologiesassociated with the PLMN in the appropriate PLMN Selector with AccessTechnology List (User Controlled or Operator Controlled selector list),as long as the specified Access Technology is also specified in theHPLMN Selector.

If the vehicle telematics unit is successfully attached to a basestation per the primary connection method 132, then it carries out thevoice channel origination process 110 of FIG. 2 which establishes thedesired modem data connection with the call center, and the process thenmoves to step 140 where it transmits vehicle data to the call centerover the established connection. The process then ends. If the primaryconnection attempt fails, then the retry strategy involves a secondaryconnection attempt 134 referred to herein as the MRA (most recentlyattached) connection process. In general, the MRA connection process 134involves selecting a PLMN or other wireless carrier system recently usedin placing a previous call, carrying out a cell selection process usingthe selected carrier system, attaching to a selected base station, andoriginating the IMCC to the call center via the attached base station.If this does not work, then the method further comprises repeating thecarrier system selection, cell selection, and attaching steps usingother previously used carrier systems until either a successfulorigination is made or until origination via a base station has beenunsuccessfully attempted on all selected wireless carrier systems. Thiscan be done using a list of the previously used PLMNs or other carriersystems that is maintained at the vehicle and that is updated each timea new call is originated. The secondary connection method 134 is furtherdescribed farther below in connection with FIG. 6.

As with the primary connection method, if this secondary connectionattempt is successful, then the voice channel cellular connection isoriginated and the modem data connection set up as indicated at step 110of FIG. 2. If the secondary connection attempt fails, the process movesto step 136 where a check is made to determine whether the call beingplaced is permitted to revert to a voice-only call if the modem dataconnection cannot be established (voice fallback)—for example, becauseof an outage of an in-band data modem bank in the call center or amalfunction of the in-band modem in the VTU 30. In general, most voicecalls are permitted to switch to voice fallback since the desiredcommunication is speech, whereas non-voice calls are not. This can bespecified in the call connection table of FIG. 3. Examples ofspeech-based calls for which voice fallback is desired include emergencyand collision detection calls, roadside assistance calls, and telematicsservices enrollment calls from the vehicle. In each case, live speechwith the occupant is desired and so the establishment of a voice-onlycall still enables the desired communication to be carried out. Examplesfor which no voice fallback is desired can include automated dataupload, downloading of navigation routes to the vehicle, andnotification to the call center of a vehicle theft using an on-boardtheft detection system. As will be appreciated, some or all of theselatter types of data communication calls may not even involveinteraction with an occupant so there may be no benefit in providing avoice-only connection in the event that a data connection cannot beestablished.

If voice fallback is not permitted for the call being placed, then theprocess 108 is considered to have failed, as indicated at block 148. Inthis case, if the call connection table specifies an alternative calltype for the call being placed, then the alternative connection strategycan be carried out, as indicated by block 120 of FIG. 2. If voicefallback is permitted, then the process moves to block 138 where atertiary connection attempt is made. In general, this tertiary attemptimplements a comprehensive connection strategy that includes attemptingreselection of one or more PLMNs using a manual network selection modesupported by the GSM cellular system. If a reselected PLMN issuccessfully obtained, then the telematics unit attempts to attach to abase station within the reselected PLMN and, if successful, it thenproceeds to originate the IMCC call and establish the modem dataconnection. The process then moves to block 140 where the desired datais transmitted to the call center and the call then switched to voicemode, if desired.

If the tertiary connection attempt fails, then the process goes intovoice fallback in which it attempts to originate a voice-only call bysetting up a voice channel cellular connection without establishing amodem data connection. This is the same process as is used forestablishing a voice-only call where it was determined at block 130 thatno data connection was needed. Thus, for voice-only calls, the methodattempts to establish a voice channel cellular connection forcommunication of speech without using the primary, second, or tertiaryconnection attempts; whereas, for IMCC calls that are permitted voicefallback, attempted establishment of a voice channel cellular connectionoccurs only if primary, secondary, and tertiary connection attemptsfail. In either circumstance, the process moves to block 142 where thetelematics unit places a voice-only call. In the illustrated embodiment,this is done using the most recently attached PLMN which can be lookedup from the list noted above that is used in the MRA connection process134 and maintained at the vehicle. Additional attempts can be made toacquire a suitable base station if the latest registered PLMN (RPLMN) isnot found. For example, acquisition of each of the PLMNs in the latestRPLMN's BCCH Allocation list (BA list) can be attempted and, if nonefound, then the telematics unit can go through a full acquisitionprocess similar to that upon done by wireless GSM cellular devices uponpower on. As will be understood by those skilled in the art, to placethe voice-only call, the telematics unit can use Teleservice ID 11 (GSMspeech teleservice for the regular telephone service) per TS23.018 BasicCall Handling using a specified voice fallback number.

Although the voice-only calls are established on the basis that a modemdata connection is not needed or not available, if the call attempted atbock 142 is successful, then if desired, call center can nonethelessattempt to establish a modem data connection (e.g., by sending asuitable signaling tone the telematics unit), in which case thetelematics unit can be configured to respond to this and switch to datamode for an initial vehicle data upload. Once done, the call can beswitched to voice mode for communication with the vehicle occupant.Regardless of whether an initial data mode connection is attempted,after the call is successfully established, the process moves from step142 to step 144 where the call is connected at the call center to anadvisor to supply assistance to the vehicle occupant.

If the voice-only call attempt fails, then the process moves to block146 where a check is made to determine if the particular call beingplaced is of the type that has a specified extended track. This can bedone using the call connection table of FIG. 3. If an extended track isspecified, such as for a collision or emergency call, then the processreturns to retry the comprehensive connection approach 138. Thus, formore important calls, the system continues to re-attempt a connectionuntil successful or, if desired, a maximum number of retries isattempted. If no extended track is specified, then the connection retryprocess 108 is considered to have failed, as indicated at block 148.

Turning now to FIG. 5, there is shown further details of the primaryconnection strategy 132 of FIG. 4. In general, the method involvesverifying that the telematics unit is attached to a base station,attempting to originate a connection with the call center using theattached base station and, if that fails, then iteratively attempting toattach and connect via neighboring base stations identified by a BA listobtained from the attached base station. The method begins at step 150where a check is made to determine if there is a currently-attached basestation, such as one to which the telematics unit was already attachedto prior to receiving the request to connect to the call center. If so,the process can proceed to attempt origination at step 156. If not, thenthe telematics unit executes an idle mode process 152 which can be thesame or different than that discussed above in connection with FIG. 4.At step 154 it is determined whether the idle mode process resulted inattaching to a reselected base station. If not, then the primaryconnection attempt is considered a failure. As discussed above, whenused as a part of the FIG. 4 data connection retry method 108, failureof this primary connection attempt is followed by a secondary connectionprocess. Although the checks for determining if the telematics unit hassuccessfully attached to a base station are shown in FIG. 5 and otherfigures as discreet steps, it will be appreciated that if, after initialdetermining that there is not an attached base station (e.g., nodecodable BCCH) and during the process the BCCH subsequently becomesdecodable, the telematics unit can continue on with the connectionprocess.

If at block 154 it is determined that the telematics unit successfullyattached to a reselected base station, then the process continues toblock 156 where an origination process is carried out to establish thevoice channel cellular connection via the attached base station. Ifsuccessful, the method ends and the telematics unit and call center canproceed to establish a modem data connection. If the origination attemptfails, then the process moves to block 158 where an iterative processbegins in which the BA list received from the attached base station isused to attempt attachment to neighboring base stations that are on thelist. Thus, assuming not all base stations on the list have yet beentried, the process goes to step 160 where the next base station on thelist is identified and attachment attempted using the BCCH identifiedfor that next base station. For the purpose the telematics unit receivesand decodes base station information via the BCCH and attempts to attachto a neighboring base station using the decoded information. This can bedone via an idle mode process, as indicated at step 162. The idle modeprocess can also be used in the event a PLMN Change Event Interrupt 164occurs anytime during the primary connection attempt process. If aninterrupt 164 is received, the idle mode process can be used to carryout a PLMN reselection process and then attach to a base stationfollowing that reselection. For a reselected PLMN, the iterative processof FIG. 5 can be carried out until successful or all base stationsidentified from the BA list for the attached base station from thereselected PLMN have been tried.

From step 162 the process moves to step 166 where a check is made todetermine if the telematics unit was able to attach to a base station.If so, then origination is attempted with that attached base station. Ifnot, then the process loops back to step 158 to iteratively try the nextbase station on the BA list. Once all base stations on the active BAlist have been tried, as determined at block 158, then the process caneither return failed or, as shown, can check to determine at step 168whether an alternative connection strategy exists. This can beidentified from the alternative call type column of the call connectiontable of FIG. 3. For example, where a packet data connection isidentified as a permissible alternative call type, then the process canswitch to the packet data retry process 116. If none is available, thenthe secondary connection attempt fails; however, if an alternativeconnection strategy is available, then that strategy is carried out atstep 170 with a call origination attempt 156 then being made.

FIG. 6 depicts the secondary connection method 134 which is a mostrecently attached (MRA) process used to attempt origination via one ofthe wireless carrier systems to which the telematics unit has recentlysuccessfully used. This process begins following failure of the primaryconnection method to successfully originate the IMCC call. In general,the MRA connection process 134 involves selecting a carrier systemrecently used in placing a previous call, carrying out a cell selectionprocess using the selected carrier system, attaching to a selected basestation, and originating the IMCC to the call center via the attachedbase station. For this purpose, a list of carrier systems is maintainedat the vehicle, and this list is referred to herein as the MRA list. Itincludes the carrier systems that the telematics unit has previouslyregistered with in reverse chronological order (i.e., with the mostrecently attached carrier system listed first). In 2G/2.5G GSM (GPRS andEDGE) and 3G W-CDMA (UMTS, HSPA) cellular systems, the wireless carriersystems are identified by PLMNs to which the cellular chipset 50 in theVTU 30 is attached by updating its location. Thus, in one embodiment,the list can be of those PLMNs for which the telematics unit haspreviously successfully completed an IMSI attach procedure. Given thatthe primary connection method has failed, the MRA connection processseeks to attach to a base station using recently registered PLMNs forwhich there can be assumed a reasonable likelihood of success within aparticular geographic coverage area.

Initiation of the MRA connection process results when the system hasdetected or otherwise determined failure of the first connection attemptwith the call center via an attached base station of a registered PLMN.In response to that determination, the process accesses the MRA list andcarries out the iterative process described below. Typically, thetelematics unit will come into the MRA connection process with anattached base station for the last PLMN used by primary connectionmethod. This is confirmed by step 176 such that the MRA connectionprocess will immediately terminate as failed if no such base station isattached. In other embodiments, the initially attached base station maynot be required. Assuming the telematics unit is attached, the processmoves to step 178 where the process accesses the MRA list of PLMNs andselects the next PLMN in the list. This can be the first entry in theMRA list or, where it is assumed that the first entry was one of theones unsuccessfully used in the primary connection attempt, step 178 canbe used to start out with the second entry in the MRA list. At step 180a check is made to determine if the reselected PLMN is the same as thatattempted during the primary connection method. If so, there is no needto attempt on that PLMN again, and the process can select the next entryin the MRA list at block 184 after first verifying at step 182 thatthere are still untried entries remaining in the list. The process thenloops back to step 180 to again confirm that the currently-selected PLMNwas not one used in the primary connection method.

Once a PLMN is selected, the process moves to step 186 where it executesan idle mode process that can be the same as those described above inconnection with FIG. 4. If an attached base station is acquired, asindicated at step 188, then a voice channel origination 190 isattempted, and this can be the same as the origination process 110identified in FIG. 2. If origination is successfully, then thetelematics unit and call center can proceed to establish the modem dataconnection and communicate data as desired. If origination fails, thenthe process loops back up to block 182 to again check for more entriesin the list. If the telematics unit does not attach to the selected basestation resulting from step 186, then the process moves from block 188to step 192 where a check is made to determine if all BCCH carriers(i.e., all neighboring base stations) have been tried. This can be doneby obtaining the BCCH Allocation (BA) list for the base station selectedin step 186, and then one by one attempting to attach to the neighboringbase stations identified from the BA list. This involves scanning theBCCH carriers in the BA list received from the selected base station.Assuming there are untried nearby base stations, the process moves tostep 194 where the next base station from the BA list is selected andthe idle mode process is again executed for that next base station in anattempt to attach. Thus, it will be appreciated that the MRA connectionprocess 134 involves iteratively going through the MRA list one PLMN ata time, selecting a base station for each PLMN using an idle modeprocess, attempting to attach to the selected base station and, ifunsuccessful, attempting to attach to each of a number of neighboringbase stations identified by the selected base station and, once anattached base station is acquired, attempting to originate the voicechannel cellular connection via the attached base station. Iforigination fails on an Absolute Radio Frequency Channel Number (ARFCN)in the received BA list, the telematics unit can determine the nextavailable ARFCN that corresponds to that PLMN entry to search for thenext suitable cell. Upon failure of the origination process, thetelematics unit can perform PLMN/cell reselection via the idle modeprocess on all BCCH ARFCNs in the received BA list of its correspondingPLMN entry in the MRA list.

As discussed above in connection with FIG. 5, the idle mode process canalso be used in the event a PLMN Change Event Interrupt 196 occursanytime during the secondary connection attempt process. If an interrupt196 is received, the idle mode process 186 can be used to carry out aPLMN reselection process and then attach to a base station followingthat reselection. For a reselected PLMN, the iterative process of FIG. 6can be carried out until successful or all base stations identified fromthe BA list for the attached base station from the reselected PLMN havebeen tried. The overall process can then either restart or continue withPLMNs from the MRA list. For example, when a PLMN Change Event 196occurs during the MRA connection process 134, and the telematics unit isunable to camp on a new PLMN and its associated BA list, the telematicsunit can check to determine if it has retried on all PLMN entries in theMRA list.

Although not shown in FIG. 6, at the successful conclusion of the MRAconnection process where an origination has successfully occurred, theMRA list can be updated with the newly reselected RPLMN. As will beappreciated, the MRA list can be maintained at the vehicle by storing itin the telematics memory 54 or some other suitable location.

FIG. 7 shows the tertiary connection method 138 which is a comprehensiveconnection method utilized if the primary and secondary methods fail andthe call type is one for which voice fallback is permitted. In general,the method involves using a supported manual network selection mode toattempt origination over any available wireless carrier system, andpreferably this is done using a pre-established order of priority ofcarrier systems so that, for example, PLMNs most likely to besuccessfully attached to are attempted first. The method starts at step200 where the telematics unit scans all band supported by the accesstechnologies in the home PLMN (HPLMN) selector. As will be appreciatedby those skilled in the art, for a GSM telematics unit, the SIM cardcontains a HPLMN selector that identifies the access technologiesavailable for use by the telematics unit. This includes all of the GSMbands for the full ARFCN scanning. Once all available PLMNs have beenfound, the process moves through a loop control block 202 to step 204where it attempts to reselect a PLMN according to a predefined orderusing the manual network selection mode supported by the GSMspecification used by the PLMNs. In one embodiment, the order can be asfollows:

1) the latest PLMN in the MRA list;

2) the HPLMN (home PLMN associated with the telematics unit);

3) a PLMN on the user controlled or operator controlled selector list(EFPLMNwAcT/EFOPLMNwAcT) in prioritized order;

4) other PLMN not in any list; and

5) a PLMN in a forbidden PLMN list or forbidden location area identity(LAI) list if no other PLMN is found by the telematics unit.

Given a selected PLMN using the process above, the telematics unitattempts to attach or otherwise access the selected PLMN and, if notsuccessful at block 206, loops back up to determine at step 202 if thereare any remaining PLMNs to try and, if so selects the next PLMNaccording to the pre-established order. If the PLMN is able to beaccessed, then an idle mode process is used to attempt cell selectionand attachment to the selected base station, as described above. This isdone at step 210. Assuming the telematics unit attaches to the selectedbase station, then origination of a voice channel cellular connection isattempted at step 212 and this can be maintained as a voice-only call ora modem data connection (IMCC call) can be attempted if desired.Although not shown, the tertiary connection process can includeattempted attachment to neighboring base stations using a BA list if thetelematics unit is unable to attach to the selected base station for theselected PLMN.

As discussed above in connection with FIGS. 5 and 6, the idle modeprocess can also be used in the event a PLMN Change Event Interrupt 214occurs anytime during the tertiary connection attempt process. If aninterrupt 214 is received, the idle mode process 208 can be used tocarry out a PLMN reselection process and then attach to a base stationfollowing that reselection. For a reselected PLMN, the iterative processof FIG. 7 can be carried out until successful or all base stationsidentified from the BA list for the attached base station from thereselected PLMN have been tried. The overall process can then eitherrestart or continue with PLMNs identified at the start of the process.

It is to be understood that the foregoing is a description of one ormore preferred exemplary embodiments of the invention. The invention isnot limited to the particular embodiment(s) disclosed herein, but ratheris defined solely by the claims below. Furthermore, the statementscontained in the foregoing description relate to particular embodimentsand are not to be construed as limitations on the scope of the inventionor on the definition of terms used in the claims, except where a term orphrase is expressly defined above. Various other embodiments and variouschanges and modifications to the disclosed embodiment(s) will becomeapparent to those skilled in the art. All such other embodiments,changes, and modifications are intended to come within the scope of theappended claims.

As used in this specification and claims, the terms “for example,” “forinstance,” “such as,” and “like,” and the verbs “comprising,” “having,”“including,” and their other verb forms, when used in conjunction with alisting of one or more components or other items, are each to beconstrued as open-ended, meaning that that the listing is not to beconsidered as excluding other, additional components or items. Otherterms are to be construed using their broadest reasonable meaning unlessthey are used in a context that requires a different interpretation.

The invention claimed is:
 1. A connection method for use by a vehicletelematics unit to establish a wireless telephone connection between thetelematics unit and a call center over a GSM cellular system, comprisingthe steps of: (a) determining that a call attempted using a primaryconnection strategy and a secondary connection strategy has failed; (b)detecting that the call attempted using the primary strategy andsecondary strategy is permitted to revert to a voice-only call when amodem data connection cannot be established, and if so, then: (c)selecting an available PLMN using a manual network selection modesupported by the GSM cellular system; (d) selecting a base stationwithin the selected PLMN; (e) attempting to attach to the selected basestation; (f) attempting origination of a voice channel cellularconnection if the telematics unit is attached to a base station; and (g)iteratively repeating steps (c) through (f) for each available PLMN thathas been recently used to place a call.
 2. The connection method as setforth in claim 1, wherein step (c) further comprises determining allavailable PLMNs and then attempting to select from among the availablePLMNs in a pre-established order.
 3. The connection method as set forthin claim 2, wherein step (c) further comprises attempting to attach toavailable PLMNs using the manual network selection mode, in thefollowing order: i) a PLMN listed in a most recently attached (MRA)list; ii) a home PLMN associated with the telematics unit; iii) otheridentified PLMNs; and iv) a PLMN listed in a forbidden PLMN list or aforbidden LAI list if no other PLMN is found.
 4. The connection methodas set forth in claim 3, wherein the other identified PLMNs comprise aPLMN on a user controlled or operator controlled selector list.
 5. Theconnection method as set forth in claim 2, wherein the telematics unithas associated therewith a home PLMN selector and access technologies inthe home PLMN selector, and wherein step (c) further comprisesdetermining all available PLMNs by scanning all bands supported by theaccess technologies in the home PLMN selector.
 6. The connection methodas set forth in claim 1, wherein step (g) further comprises attemptingto attach to the base stations using an idle mode process.
 7. Theconnection method as set forth in claim 1, further comprising the stepsof: receiving a PLMN change event interrupt; carrying out a PLMNreselection process based on the interrupt; and attaching to a basestation following PLMN reselection.
 8. The connection method as setforth in claim 7, wherein the step of carrying out a PLMN reselectionprocess further comprises the step of executing an idle mode processinvolving PLMN reselection.
 9. The connection method as set forth inclaim 1, further comprising carrying out steps (c) through (g) as a partof a voice fallback connection attempt.
 10. The connection method as setforth in claim 1, wherein, in step (e), if attaching to the selectedbase station is not successful, then step (e) further comprisesattempting to attach to another base station identified on a BCCHAllocation list for the selected base station.
 11. The connection methodas set forth in claim 1, wherein step (f) further comprises attemptingorigination of the voice channel cellular connection as an in-band modemcellular call.